Microorganisms and processes for producing L-glutamine

ABSTRACT

The present invention provides novel microorganisms,  Brevibacterium lactofermentum  CJJA21 (Accession No. KCCM-10222), which is resistant to sodium azide, and  Brevibacterium lactofermentum  CJJA22 (Accession No. KCCM-10223), which is resistant to α-aminobutyric acid. These microorganisms are capable of producing L-glutamine in a higher yield than the known strains. The present invention further provides processes for producing L-glutamine using the microorganisms of the invention.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 10/198,274filed Jul. 17, 2002, now U.S. Pat. No. 6,984,506 which in turn is acontinuation application of International Application Ser. No.PCT/KR01/01952 filed Nov. 15, 2001 and published as WO 02/40643, whichclaims priority to Korean Application Ser. No. 2000/68284 and KoreanApplication Ser. No. 2000/68285, both filed Nov. 17, 2000. Saidapplications are included herein in their entirety by reference.

BACKGROUND

L-glutamine is an amino acid widely used as medicines such astherapeutic agents of gastroenterologic disorders, potentiators of liverand brain functions, immuno-enhancement agents, and therapeutic agentsof gastric ulcer and alcoholism, etc., cosmetics such as moisturizers,etc., and health foods such as sports nutrients and nutrients forpatients, etc.

According to the prior art, L-glutamine was obtained fromsulfaguanidine-resistant strains (Japanese Patent, Laid-Open No.Sho53-17675), azaserine-resistant strains (Japanese Patent Laid-Open No.Sho55-148094) penicillin-sensitive strains (Japanese Patent Laid-OpenNo. Hei04-088994), tyrosine-glutamic acid (tyr-glu)-resistant strains(Japanese Patent Laid-Open No. Hei02-186994) and the like.

SUMMARY OF THE INVENTION

The present invention relates to novel microorganisms producingL-glutamine and to processes for producing L-glutamine using the same.More specifically, the invention relates to Brevibacteriumlactofermentum CJJA21 (KCCM-10222) resistant to sodium azide andBrevibacterium lactofermentum CJJA22 (KCCM-10223) resistant toD,L-α-amino-n-butyric acid: α-ABA), both of which are capable ofproducing L-glutamine in a higher yield than the known strains, and toprocesses for producing L-glutamine using the same.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors performed extensive studies to develop novelstrains, which are capable of producing L-glutamine in a highproductivity. We contemplated that strains resistant to sodium azide, arespiratory inhibitor, or to α-aminobutyric acid, an analogue of anamino acid, isoleucine, would have the increased productivity ofL-glutamine. Thus, we screened sodium azide or α-aminobutyricacid-resistant strains from an original strain Brevibacteriumlactofermentum KFCC-10680 (Korean Patent Publication No. 91-7818). Thisstrain was deposited as KFCC-10680 with the Korean Culture Center ofMicroorganisms on Oct. 8, 1989 for the purpose of patent procedures anddescribed in Korean Patent No. 91-7818, issued on Oct. 2, 1991. As aresult, we identified that the sodium azide resistant strainBrevibacterium lactofermentum CJJA21 strain KCCM-10222 or α-aminobutyricacid-resistant strain Brevibacterium lactofermentum CJJA21 strainKCCM-102232 produce L-glutamine in a higher yield than the known strainsand thus, completes the present invention. The strains are high GCcontent, gram-negative cubacteria, which are nonsporeforming and arenon-pathogenic. The strains are cysteine-demanding and aerobic, with anoptimum temperature for cultivation of 30° C. and an optimum pH of 6.8.

The present invention provides microorganisms producing L-glutamine andprocesses for producing L-glutamine using the same. The microorganismsaccording to the present invention are Brevibacterium lactofermentumCJJA21 (KCCM-10222) having a resistance to sodium azide andBrevibacterium lactofermentum CJJA22 (KCCM-10223) having a resistance toα-aminobutyric acid, both of which produce L-glutamine in a high yield.Further, the processes for producing L-glutamine according to thepresent invention is characterized by the activation of Brevibacteriumlactofermentum CJJA21 or Brevibacterium lactofermentum CJJA22 followedby the cultivation of the activated strains.

In the present invention, mutants were induced by the following methods.Brevibacterium lactofermentum KFCC-10680 was treated withN-methyl-N′-nitro-N-nitrosoguanidine (NTG), a conventional mutagen andthen, spread on a minimal medium (Medium 1) containing 500 mg/l ofsodium azide thereby to obtain strains having a resistance to 500 mg/lof sodium azide.

More specifically, Brevibacterium lactofermentum KFCC-10680, which hadbeen previously activated by cultivation on an activation medium (Medium2) for 16 hours, was cultivated for 14 hours on a seed medium (Medium 3)sterilized at 121° C. for 15 minutes. Then, 5 mL of the culture mediumwas washed with 100 mM citrate buffer and thereto was added NTG at afinal concentration of 200 mg/l. After 20 minutes, the medium was washedwith 100 mM phosphate buffer. The strains treated with NTG were spreadon a minimal medium (Medium 1) and the death rate was measured. As aresult, the death rate was 85%.

In order to obtain sodium azide-resistant mutants, the NTG-treatedstrains were spread on a minimal medium (Medium 1) containing sodiumazide at a final concentration of 500 mg/l and then, cultivated at 30°C. for 6 days to obtain sodium azide-resistant strains. The obtainedresistant mutants were cultivated in a shaking Erlenmeyer flaskcontaining a glutamine production medium (Medium 4) for 72 hours therebyto select a sodium azide-resistant strain producing L-glutamine in a 10%or more higher yield than the original strain, Brevibacteriumlactofermentum KFCC-10680. The obtained strain was designated as CJJA21.Brevibacterium lactofermentum CJJA21 was deposited under the BudapestTreaty to the Korean Culture Center of Microorganisms whose address isHongje-dong, Seodaemun-gu, Seoul, on Oct. 20, 2000, with the AccessionNo. KCCM-10222.

In addition, Brevibacterium lactofermentum KFCC-10680 was activated andcultivated in the substantially same manner as above. It wassubsequently treated with NTG in the substantially same manner as above.In order to obtain α-aminobutyric acid-resistant mutants, the NTGtreated strains were spread on a minimal medium (Medium 1) containingα-aminobutyric acid at a final concentration of 15 g/1 and then,cultivated at 30° C. for 6 days to obtain α-aminobutyric acid-resistantstrains. The obtained resistant mutants were cultivated in a shakingErlenmeyer flask containing a glutamine production medium (Medium 4) for72 hours thereby to select a α-aminobutyric acid-resistant strainproducing L-glutamine in a 10% or more higher yield than the originalstrain, Brevibacterium lactofermentum KFCC-10680. The obtained strainwas designated as CJJA22. Brevibactertium lactofermentum CJJA22 wasdeposited under the Budapest Treaty to the Korean Culture Center ofMicroorganisms whose address is Hongje-dong, Seodaemun-gu, Seoul, onOct. 20, 2000, with the Accession No. KCCM-10223.

Culture media employed in the present invention have the followingcompositions:

Medium 1: Minimal medium

Glucose 1.0%, Ammonium Sulfate ((NH₄)₂SO₄) 0.4%, Magnesium Sulfate(MgSO₄. 7H₂O) 0.04%, Potassium Dihydrogen Phosphate (KH₂PO₄) 0.1%, Urea0.1%, Thiamine HCl 0.0001%, Biotin 200 μg/l, Agar, pH 7.0

Medium 2: Activation medium

Beef extract 1%, Polypeptone 1%, Sodium Chloride (NaCl) 0.5%, YeastExtract 0.5%, Agar 2%, pH 7.2

Medium 3: Seed medium

Glucose 5%, Bactgpeptone 1%, Sodium Chloride (NH₄Cl) 0.25%, YeastExtract 1%, Biotin 3 μg/l, Urea 0.4%, pH 7.0

Medium 4: Glutamine production medium

Glucose 4.0%, Ammonium Chloride (NH₄Cl) 3.0%, Soy Protein AcidHydrolyzate 0.3%, Calcium Carbonate (CaCO₃) 5%, Calcium Chloride (CaCl₂)0.1%, Magnesium Sulfate (MgSO₄.7H₄O) 0.05%, Potassium DihydrogenPhosphate (KH₂PO₄) 0.15%, Potassium Monohydrogen Phosphate (K₂HPO₄)0.15%, Urea 0.3%, Thiamine, HCl 2 mg/l, Biotin 5 μg/l, Ferric Sulfate(FeSO₄.7H₂O) 20 mg/l, Manganese Sulfate (MnSO₄H₂O) 20 mg/l, Zinc Sulfate(ZnSO₄.7H₂O) 12 mg/l, pH 6.8.

Sodium azide-resistance of Brevibacterium lactofermentum CJJA21 is shownin the following Table 1-1.

TABLE 1-1 Sodium azide concentration (mg/l) Strain 0 100 200 300 500 800KFCC- +++ + + − − − 10680 CJJA21 +++ +++ +++ +++ ++ − +: growth, −: nogrowth, cultivation at 30° C. for 6 days

α-Aminobutyric acid-resistance of Brevibacterium lactofermentum CJJA22is shown in Table 1-2.

TABLE 1-2 α-aminobutyric acid concentration (g/l) Strain 0 1 5 10 15 20KFCC-10680 +++ ++ + − − − CJJA21 +++ +++ +++ +++ ++ − +: growth, −: nogrowth, cultivation at 30° C. for 6 days

According to the present invention, L-glutamine can be obtained in ahigher yield than the prior art. In some embodiments of the invention,about 10% more L-glutamine, more preferably about 15% more L-glutamineis produced by microorganisms of the invention than by wild-type strainsgrown under the same conditions. This improvement is illustrated by,inter alia, Examples 1–4. The obtained L-glutamine is useful formedicines such as therapeutic agents of gastroenterologic disorders,potentiators of liver and brain functions, immuno-enhancement agents,therapeutic agents of gastric ulcer and alcoholism, etc., cosmetics suchas moisturizers, etc., and health foods such as sports nutrients andnutrients for patients, etc.

EXAMPLES

This invention will be better understood from the following examples.However, one skilled in the art will readily appreciate the specificmaterials and results described are merely illustrative of, and are notintended to, nor should be intended to, limit the invention as describedmore fully in the claims which follows thereafter.

Example 1

Strain: Brevibacterium lactofermentum CJJA21 Strain KCCM-10222

Fermentation Medium: Glucose 4.0%, Ammonium Chloride (NH₄Cl) 3.0%, SoyProtein Acid Hydrolyzate 0.3%, Calcium Carbonate (CaCO₃) 5%, CalciumChloride (CaCl₂) 0.1%, Magnesium Sulfate (MgSO₄.7H₂O) 0.05%, PotassiumDihydrogen Phosphate (KH₂PO₄) 0.15%, Potassium Monohydrogen Phosphate(K₂HPO₄) 0.15%, Urea 0.3%, Thiamine, HCl 2 mg/l, Biotin 5 μg/l, FerricSulfate (FeSO₄.7H₂O) 20 mg/l, Manganese Sulfate (MnSO₄.H₂O) 20 mg/l,Zinc Sulfate (ZnSO₄.7H₂O) 12 mg/l, pH 6.8 (the same as Medium 4).

Fermentation procedure and result: To a shaking Erlenmeyer flask of 250mL was injected 20 mL of the fermentation medium. The medium wassterilized at 121° C. for 15 minutes. Thereto was inoculated 1 loopfullof strains activated by the cultivation on an activation medium (Medium2) at 30° C. for 16 hours and then, cultivated while shaking at 30° C.for 48 hours. The L-glutamine concentration of the fermented broth isshown in Table 2.

TABLE 2 KFCC-10680 CJJA21 (Original Strain) (Variant) Concentration of12.6 14.5 glutamine (g/l)

Example 2

Strain: Brevibacterium lactofermentum CJJA21 Strain KCCM-10222

Fermentation medium: Glucose 10%, Ammonium Chloride (NH₄Cl) 4.5%, SoyProtein Acid Hydrolyzate 0.5%, Calcium Carbonate (CaCO₃) 5%, CalciumChloride (CaCl₂) 0.1%, Magnesium Sulfate (MgSO₄.7H₂O) 0.05%, PotassiumDihydrogen Phosphate (KH₂HPO₄) 0.15%, Potassium Monohydrogen Phosphate(K₂HPO₄) 0.15%, Urea 0.3%, Thiamin (Thiamine.HCl) 2 mg/l, Biotin 5 μg/l,Ferric Sulfate (FeSO₄.7H₂O) 20 mg/l, Manganese Sulfate (MnSO₄.H₂O) 20mg/l, Zinc Sulfate (ZnSO₄.7H₂O) 12 mg/l, pH 6.8.

Fermentation procedure and result: To a shaking Erlenmeyer flask of 250mL was injected 20 mL of the fermentation medium. The medium wassterilized at 121° C. for 15 minutes. Thereto was inoculated 1 loopfullof strains activated by the cultivation on an activation medium (Medium2) at 30° C. for 16 hours and then, cultivated while shaking at 30° C.for 72 hours. The L-glutamine concentration of the fermented broth isshown in Table 3.

TABLE 3 KFCC-10680 CJJA21 (Original Strain) (Variant) Concentration of31.5 37.1 glutamine (g/l)

As shown in Table 3, Brevibacterium lactofermentum CJJA21 of the presentinvention produced L-glutamine in a 10% or more higher yield than theoriginal strain, Brevibacterium lactofermentum KFCC-10680.

Example 3

Brevibacterium lactofermentum CJJA22 strain KCCM-10223 was cultivatedaccording to the substantially same method as in Example 1. TheL-glutamine concentration of the fermented broth is shown in Table 4.

TABLE 4 K-FCC-10680 CJJA22 (Original Strain) (Variant) Concentration of12.4 14.1 glutamine (g/l)

Example 4

Brevibacterium lactofermentum CJJA22 strain KCCM-10223 was cultivatedaccording to the substantially same method as in Example 2. TheL-glutamine concentration of the fermented broth is shown in Table 5.

TABLE 5 KFCC-10680 CJJA22 (Original Strain) (Variant) Concentration of31.1 36.5 glutamine (g/l)

1. Isolated Brevibacterium lactofermentum CJJA21 strain KCCM-10222. 2.The isolated Brevibacterium lactofermentum CJJA21 strain of claim 1wherein said strain is resistant to sodium azide.
 3. IsolatedBrevibacterium lactofermentum CJJA22 strain KCCM-10223.
 4. The isolatedBrevibacterium lactofermentum CJJA22 strain of claim 3 wherein saidstrain is resistant to α-aminobutyric acid.